[ Oil & Gas ]
By Joanne McIntyre & John Butterfield
Photo : © Shell Global Solutions International
[ Oil & Gas ]
When Shell first announced the project in the early 2010s , the dimensions of the Prelude were astonishing . It was five times larger than the largest LNG carrier at the time , measuring 488m long and 74m wide , and would displace more water than six aircraft carriers . Stood on end , it would be taller than the Petronas Towers in Kuala Lumpur . Easily taking the records for the world ’ s largest FLNG vessel and the biggest offshore facility , Prelude is operated by Shell , in a joint venture with INPEX ( 17.5 %), KOGAS ( 10 %) and OPIC ( 5 %).
Original feature story
Read our feature story based on interviews with key engineers from SBM and Shell Global Solutions when Prelude was under construction . ‘ FLNG Prelude : the world ’ s biggest floating structure ’ provides insights into the duplex and stainless steel equipment
When bigger is better …
Prelude FLNG , the world ’ s biggest floating structure
Bigger is better At just under half a kilometre in length Prelude contains 260,000 metric tons of steel – more than was used in the original World Trade Centre in New York . A huge amount of stainless steels , including duplex grades , are used in the project . The FLNG was designed to produce 3.6 MMtpa of LNG , 1.3 MMtpa of condensate and 0.4 MMtpa of LPG per annum – that ’ s more than Hong Kong uses each year . Although Shell did not disclose the cost of the vessel , Reuters reported that industry analysts estimate the price tag to be between USD 10.8 – 12.6 billion . The first shipment of LNG was offloaded from Prelude in June 2019 .
What is FLNG ? Floating LNG ( FLNG ) consolidates the traditional offshore to onshore LNG infrastructure into a single facility that is based over the fields . The FLNG facility gathers , processes , stores and offloads natural gas and condensate products at sea . FLNG removes the need for pipelines to shore , dredging and onshore works and therefore significantly limits the disturbance to the surrounding environment and in the right conditions , reduces development on board and the challenges of testing the massive forgings . Scan the QR code or CLICK HERE
costs . It is also a competitive solution for fields like Prelude , that are very remote and hard to access . The Prelude FLNG facility is moored in 250 metres of water , by four groups of mooring chains . Each mooring chain is held to the sea floor by piles . The facility has been designed to withstand severe weather , including a ‘ 10,000 year ’ storm , and will remain onsite during all conditions . Seven production wells will feed gas and condensate from the reservoirs via four flexible risers into the facility . All subsea connections join the facility via the turret . The turret ’ s swivel design enables the facility to pivot according to wind and sea conditions while it remains fixed to the sea floor . The Prelude FLNG facility has thrusters to ensure it remains steady during production and offloading , but it is a fixed facility , with no means of
Imagine the largest LNG carrier in the world … then multiply the size by a factor of five . This gives you an idea of just how big Prelude - the world ’ s first floating liquefied natural gas ( FLNG ) project - really is . At just under half a kilometre in length and 73 meters wide , Prelude will eventually contain 260,000 metric tons of steel – that ’ s more than was used in the original World Trade Centre in New York . With an expected life cycle of at least fifty years , a huge amount of stainless steels , including duplex grades , are used in the project . Stainless Steel World met Andrew Barnes of Shell Global Solutions and Anthony Pearson of SBM Offshore at the recent Duplex Seminar & Summit , where they presented this mammoth project . Andrew provided an overview of the project and Anthony talked about SBM Offshore ’ s contribution , as providers of the turret , and some of the materials challenges it is presenting .
propulsion . The management of subsea wells and manifolds is carried out via umbilicals connected through the turret to the control room on the facility . The processing of gas and condensate occurs in modules onboard that occupy an area approximately one quarter the size of a typical onshore LNG plant . Safety of the FLNG facility has been paramount during its design , and its safety profile is predicted to be inline with modern offshore oil and gas facilities . The FLNG design has gone through extensive testing programs and simulations to ensure it has the ability to remain connected and moored to the sea floor throughout all weather conditions .
17200 kg duplex castings Given the impressive scale of the Prelude FLNG it ’ s no surprise that some of the individual forged parts are
26 Stainless Steel World September 2024 www . stainless-steel-world . net